It could have impacted land, but we would have sat pictures of fire, etc. It depends how it impacts, there have been a few crashes that went straight in (Air Tran DC9, PSA BA146, United 737 in COS) All three of those impacted in populated areas, but had small debris fields. With the ocean, and currents, and not searching the right spot, it is plausable it impacted in a small space, though if it were coming straight down, it would go past mach 1 and the wings would most likely shear off. 777 has a lot of composites though, so I'm not sure how that would fare in an impact. I just think there were some inherent flaws in that plane, and it just reached the breaking point. We had a few ancient 747's that were pretty bad, they even had nicknames, "Ashes" because it was the plane that lost 3 engines over the Redoubt volcano in Alaska, "Patches" because the thing had so many rivets and patches in it, and my favorite "Christine, the hangar queen", because it was always on MX, and usually mysteriously... They all had 17,000 plus cycles on them when we got them, and they are long since turned into beer cans....